苏鲁超高压带北段夏河城岩体的形成时代及其意义  

The age of Xiahecheng intrusive body in the Northern Sulu UHP Metamorphic Belt and its Geological Implication

作　　者：宋明春[1,2] 韩景敏[3] 

机构地区：[1]中国地质科学院地质研究所 [2]山东省地质矿产勘查开发局,济南250012 [3]山东省国土资源厅

出　　处：《地质论评》2006年第5期601-608,共8页Geological Review

基　　金：国家自然科学基金项目(编号40372101)资助的成果。

摘　　要：位于苏鲁超高压变质带北段的夏河城岩体由角闪辉长岩、闪长岩和石英闪长岩组成，其中的闪长岩锆石U—Pb同位素年龄为195±17Ma。该岩体侵入于超高压变质岩中，其化学成分具Ⅰ型花岗岩特点（多数样品Na2O〉3％；所有样品A／NKC〈1．1，均含标准矿物Di，未出现标准矿物C）。苏鲁超高压变质带中，存在3类不同成因的印支期侵入岩，其同位素年龄范围在195～227Ma，与超高压变质岩退变质阶段的年龄（202-229Ma）一致，指示超高压变质作用发生在印支期岩体形成之前。这些印支期侵入岩具有不同的岩石化学特征，指示它们的岩浆成因及来源可能有比较大的差别。在此基础上，对这些侵入岩形成时的构造背景，进行了初步讨论。Xiahecheng intrusive body in northern Sulu UHP metamorphic belt consists of hornblende gabbro,diorite and quartz diorite. The zircons from the diorite yields U-Pb age of 195±17Ma. This intrusive body intrudes into UHP metamorphic rocks and is petrochemically similar to I-type granitoids , such as A/NKC〈1.1, occurrence of normative mineral Di but no normative mineral C for all analytical samples, and Na2O〉3% for most samples. The available data show that Indonisian intrusive bodies are widely exposed in the Sulu UHP metamorphic belt. Their isotopic ages from 195Ma to 227Ma are in consistent with those of retrogressive metamorphism of UHP metamorphic rocks, implying that UHP metamorphism predated the intrusion of these Indosinian intrusive bodies. The various petrochemical features of those Indosinian intrusive rocks reveal that there is probably obvious difference in their magmatic origin and derivation. And then, tectonic setting of those rocks is primarily discussed.

关 键 词：夏河城岩体 印支期侵入岩 苏鲁超高压变质带 同位素年龄 

分 类 号：P588.3[天文地球—岩石学]